1. Technical Field
The present invention relates to an electrostatic chuck system used in semiconductor fabrication processes involving substrate heating or cooling and to a semiconductor fabrication device equipped therewith.
2. Background Art
Semiconductor fabrication devices include devices that control substrate temperature to maintain it at a predetermined level. Such devices are provided with heating and cooling means for controlling substrate temperature. Depending upon the configuration of the devices, there are devices having only heating or only cooling means, and devices having both heating and cooling means. Well-known examples of specific semiconductor fabrication devices include sputtering devices, thin film deposition devices, and ion implanters.
When temperature control is performed with the aim of controlling the temperature of a substrate (for example, a semiconductor wafer made of silicon, silicon carbide, gallium nitride, indium phosphide, and the like, an article obtained by forming a film on the front and back surfaces of said wafer, or a glass substrate) in order to maintain it at an elevated or low level, the larger the difference between the target preset temperature and room temperature, the greater the warpage generated in the substrate. The extent of such warpage varies with the type and dimensions of the target substrate.
In many semiconductor fabrication devices, a substrate is electrostatically clamped to a stage using an electrostatic chuck and the electrostatically clamped substrate is then processed. In devices that process substrates after setting the temperature of the substrates to an elevated or low level, normal processing of substrate surfaces to be treated (e.g., surfaces subjected to ion implantation treatment) may be prevented by the warpage generated in the substrates.
Technology used to mitigate such substrate warpage is described, for instance, in Patent Citation 1. According to Patent Citation 1, when a substrate is disposed on a base member with a built-in heater and the substrate is electrostatically clamped, the rate of substrate temperature rise is smoothed out by changing the clamping voltage in a stepwise manner. This makes it possible to reduce substrate warpage in comparison with approaches in which a high clamping voltage is applied from the very beginning.